The present invention relates to an apparatus and a method for detecting deformations of vehicle components, in particular on a motor vehicle.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Detecting motor vehicle accidents is very important for protecting the occupants in order to initiate relevant safety measures, for example, deploying an airbag. German Offenlegungsschrift DE 10 2004 029 816 A1 discloses the provision of acceleration sensors to detect a sudden change in the speed of a motor vehicle. The acceleration sensor hereby reacts purely mechanically to deceleration of a vehicle by, for example, deflecting a seismic mass of the sensor. The electric properties between movable and fixed webs of the sensor thereby change, representing a measure for the magnitude of the acceleration/deceleration.
Disadvantageously, when using central acceleration sensors, for example in the event of a frontal impact, the acceleration force produced at a low speed is not significantly different from the acceleration force produced during the accident at a very high speed during the first 20 to 30 ms. Significant differences are encountered only at times that are greater than 30 ms, because the impact energy at the beginning of the accident is absorbed by the soft basic structure of the crash box. The rest of the body experiences only a slight acceleration/deceleration during that time. In addition, the location of the impact and the intensity of the accident can only be approximately determined.
German Offenlegungsschrift DE 10 2005 046 928 A1 detects an accident by evaluating sound produced by the body, also referred to as Crash Impact Sound Sensing (CISS). When structural components of a motor vehicle are deformed, the generated stress produces micro-fractures in the components, which is associated with the emission of sound waves from the body. Deformations of the vehicle body caused by the accident can then be identified by digitally evaluating the body sound signal. However, it is difficult to select the origin of the impact or the deformation, because the origin of the body sound is also unknown. In addition, a characteristic signal must be present to unambiguously distinguish the accident or the deformation of the vehicle body from other disturbances. This requires separation of the signal from these disturbances, which necessitates a correspondingly high computing power and a computing time of about 15 ms.
It would therefore be desirable and advantageous to obviate prior art shortcomings and to provide an improved apparatus and a method capable of unambiguously identify the location of the deformation of a vehicle component and the temporal progression of the deformation, so that the severity of the accident can be better determined. The evaluation should be performed within a very short timeframe, in particular less than 10 ms, after the crash occurs and should not require complicated computations.